DESCRIPTION (provided by investigator): Vitamin D is present in food either naturally or by fortification and included in nutritional supplements. It is also synthesized photochemically by the skin from ultraviolet B radiation. Vitamin D synthesis varies by season and with latitude as well as according to intensity of skin pigmentation. Recent research in the United States found lower circulating levels of 25 (OH) D, the primary indicator of vitamin D status, among minority women who were either pregnant or in their reproductive years. The extent to which maternal vitamin D has an influence on the course and outcome of human pregnancy remains to be more completely studied. We propose to use the HPLC method to assay cholecaliferol (vitamin D3) and ergocalciferol (vitamin D2) to assess maternal vitamin D status. This will be accomplished by analyzing existing fasting samples and data derived from the 2001-2006 cohort (N=1510) of young, low income minority gravidae from Camden, New Jersey to determine: 1. The prognostic importance of maternal vitamin D status for birth weight, gestation duration and poor pregnancy outcomes (low birth weight, preterm delivery, fetal growth restriction). 2. The relation of maternal vitamin D status to important complications of pregnancy (gestational diabetes and pre-eclampsia). 3. The relationship of maternal vitamin D status to maternal diet and supplement use, season of year, ethnicity, overweight/obesity, and other maternal characteristics. PUBLIC HEALTH RELEVANCE: This project has important public health implications for early detection and prevention of adverse pregnancy outcomes in a vulnerable population. If pregnant women who are vitamin D deficient are at risk, then screening and supplementation before conception or early in gestation before a complication develops or an adverse outcome occurs is feasible. The research also has implications for ethnic disparities during pregnancy. African American and some Hispanic groups (e.g. Puerto Ricans) are at increased risk of bearing low birth weight infants who are delivered preterm or small for gestation, of developing gestational diabetes and, some studies suggest, pre-eclampsia (1,2). If vitamin D deficiency is a risk factor for any or all of these problems then the underlying cause will have been uncovered and the disparity will be preventable. Underscoring the importance of prevention during reproductive life is the fact that small infants born to the women may be at high risk of cardiovascular disease and type 2 diabetes in later life.